1. Field of the Invention
The invention relates to a device, as well as a method for working ground surfaces or roadways.
2. Description of the Prior Art
The prior art includes, for example, EP 960 239 B1 (U.S. Pat. No. 6,565,281) or EP 1 396 581 A2 (U.S. Pat. No. 6,887,013).
The known devices for working ground surfaces or roadways, such as soil stabilizers or recyclers, are provided with a working drum which breaks up and mixes ground surfaces or roadways. In the case of hard roadways consisting of asphalt or concrete, these are milled. The working drum is surrounded by a bell-shaped drum housing which encloses the working chamber of the working drum, where said working chamber serves as a mixing chamber for mixing the worked-off ground material with a spraying agent, such as hydraulic or bituminous binding agents (foamed bitumen, emulsions, or slurries), or water. Alternatively, binding agents (such as cement or lime) may also be discharged/spread on the ground surface in front of the soil stabilizer/recycler.
In other ground working machines, such as road milling machines or surface miners, a spraying device may be provided to cool the cutting tools.
The spraying agents are sprayed into the working chamber by means of a spraying device attached at the drum housing, with several outlet nozzles of the spraying device being arranged at the drum housing and directed into the working chamber.
With the known spraying devices, the problem arises that the spraying agent can be introduced into the working chamber in a non-uniform fashion over the working width of the working drum, in particular in those cases requiring only a small volume of spraying agent and/or the working drum with the spraying device exhibits a transverse slope vis-à-vis the horizontal plane. In case of a transverse slope, a pressure gradient results along the spraying device so that a different flow rate issues at the individual outlet nozzles.
The known outlet nozzles can merely be switched on or switched off via a tappet-like closing element or can perform a cleaning function by means of the closing element. The cleaning function is useful because, even at a high spraying pressure, the worked-off material mixed with binding agents or water can get pressed into the outlet nozzles or can accumulate in the area in front of the outlet nozzle. Especially after a machine stoppage, there is the risk of the outlet nozzles being contaminated and blocked by set or hardened or dried worked-off material from the working chamber which will result in a decrease or even a complete inhibition of the spraying performance.
Consideration has been given to influencing the flow rate at the outlet nozzles by means of ball valves, throttle slide valves or iris diaphragms in order to ensure a uniform discharge of binding agents and/or water. However, a sufficient reliability of these systems is not given due to their sensitivity to thermal expansion and encrustation of the moving parts by, for example, solidified bitumen. In addition, problems are caused by the increased space requirement, and difficulties arise with the accompanying drive mechanisms, as well as due to the complicated automation of said proposed solutions.